A video game called "Re-Mission" has recently been investigated with adolescent and young adult cancer patients enrolled in a multi-site randomized controlled evaluation of the game as a psycho-educational intervention. The main focus of the trial was to determine effects of the game on self-care and other health-related outcomes. It was also considered valuable to evaluate participants' perceptions of the game as (1) acceptable as a treatment-related activity for young cancer patients, and (2) credible as an intervention designed to change patients' knowledge, attitudes and self-care behaviors relating to treatment. Although the cancer-related content of the game is informed by surveys of cancer professionals and patients themselves, acceptability and credibility with end-users have been important factors influencing the usability and efficacy of a range of psychological interventions. As part of the multi-site trial, 197 patients with cancer, between the ages of 13 and 29, were assigned to the treatment group. Most patients (148) completed a 9-item acceptability/credibility rating scale following 3-months' access to Re-Mission. These "completers" played Re-Mission more than the other patients, but did not differ from them on gender, age, or prior game experience. Responses to the questionnaire were analyzed as two factors representing acceptability and credibility. A mean rating for acceptability (4.1 on scale of 5) indicated a good level of acceptability, and mean rating for credibility (3.7 on scale of 5) indicated a moderate level of belief in the game as an effective intervention. Correlation analyses showed that whereas acceptability and credibility ratings were not significantly associated with educational level, both were significantly (p less than 0.01) and positively correlated with amount of time spent playing the video game during treatment (acceptability: r=0.26, credibility: r=0.25 ). The findings indicate that the self-care intervention video game would be a useful addition to the psycho-educational resources available to treatment teams. (Contains 1 table and 3 figures.)